Automatically energizable sonobuoy

ABSTRACT

A buoy housing includes flotation structure and an antenna movable from a retracted position inside the housing to an extended position outside the housing. An acoustic transducer is contained within a lower compartment in the housing and is attached to the housing by a flexible line. A transmitter is contained within the buoy housing and is operable to transmit from the antenna radio signals representative of acoustic signals received by the acoustic transducer. Structure is provided in the buoy housing which is responsive to contact with water for moving the antenna to the extended position and for lowering the acoustic transducer from the housing into the water for a preselected depth. A time delay device delays the lowering of the acoustic transducer from the housing for a predetermined time after the housing is placed in the body of water, in order to avoid entanglement of the acoustic transducer with towed streamers and the like.

United States Patent Schultz 1 June 20, 1972 [54] AUTOMATICALLYENERGIZABLE SONOBUOY [72] Inventor:

[52] US. Cl. ..340/2, 9/8 R, 340/2 [51] Int. Cl. ..H04b 1/59 [58] Field01 Search ..340/2, 7 R; 9/8 R [56] References Cited UNITED STATESPATENTS Primary Examiner-Benjamin A. Borchelt Assistant Examiner- H. A.Birmiel Attorney-Richards, Harris & Hubbard [5 7] ABSTRACT A buoyhousing includes flotation structure and an antenna movable from aretracted position inside the housing to an extended position outsidethe housing. An acoustic transducer is contained within a lowercompartment in the housing and is attached to the housing by a flexibleline. A transmitter is contained within the buoy housing and is operableto transmit from the antenna radio signals representative of acousticsignals received by the acoustic transducer. Structure is provided inthe buoy housing which is responsive to contact with water for movingthe antenna to the extended position and for lowering the acoustictransducer from the housing into the water for a preselected depth. Atime delay device delays the lowering of the acoustic transducer fromthe housing for a predetermined time after the housing is placed in thebody of water, in order to avoid entanglement of the acoustic transducerwith towed streamers and the like.

11 Claims, 5 Drawing Figures RiTEWE-JJUXZC 1272 SHEET 10F 2 FIG. 4

INVENTOR;

JAMES E SCHULTZ ATTORNEYS pgjrrrw'lf'fzj I??? 3-571'928 SHEET 2 [IF 2/O6 26 74 7O 84 ll I INVENTOR JAMES F SCHULTZ jam, (WW; M

ATTORNEYS FIELD OF THE INVENTION This invention relates to seismicsonobuoys, and more particularly to seismic sonobuoys whichautomatically operate in a predetermined manner after being placed in abody of water.

THE PRIOR ART Floating devices, termed sonobuoys, are presently commonlyutilized in marine seismic exploration. A typical sonobuoy includesacoustic transducers for detecting acoustic waves and also containsradio transmitter circuitry for transmitting representations of thedetected acoustic waves to a remote recording location. In operation,the sonobuoy is dropped overboard from a seismic exploration vessel anda hydrophone is suspended a predetermined distance below the floatingsonobuoy housing. The seismic exploration vessel generally tows aseismic streamer cable therebehind and also employs an acoustic source,such as an air gun or the like, which periodically generates acousticimpulses. Reflections from the acoustic impulses are detected by theseismic streamer and are recorded onboard the marine vessel. Refractionsfrom the acoustic impulses are picked up by the sonobuoy with thesuspended hydrophone, and representations of the refracted energy aretransmitted from the transmitter in the sonobuoy to a tuned receiver onthe marine exploration vessel and recorded on tape or the like. Dataobtained by such marine exploration techniques may provide basementdepth determination, velocity interface mapping, fault delineation,multiple reflection identification and the like.

Previously developed sonobuoys have sometimes required prearming ofcertain timing circuitry or the like before launching of the sonobuoyinto the water. More importantly, many prior sonobuoys have includedantennas and hydrophone suspension systems which quickly operated afterthe sonobuoy was deposited into the water. Problems thus often occurredbecause of entanglement of the suspended hydrophone with the trailingseismic streamer from the marine exploration vessel. Due to the factthat many commonly used seismic streamers are in the range of 9,000 feetor more in length, a substantial period of time thus exists whenentanglement of the suspended sonobuoy hydrophone with the streamer is adistinct possibility.

SUMMARY OF THE lNVENT ION In accordance with the present invention, asonobuoy is provided which includes a buoy housing containing anacoustic transducer. Structure is contained in the buoy housing forlowering the acoustic transducer from the buoy housing a predeterminedperiod of time alter the buoy housing is placed in the body of water toprevent entanglement thereof with towed objects. A radio transmitter iscontained within the buoy housing for transmitting indications ofacoustic signals received by the suspended acoustic transducer.

In accordance with a more specific aspect of the invention, anautomatically energized sonobuoy is provided which includes a buoyhousing with flotation structure. An antenna is movable from a retractedposition inside the housing to an extended position outside the housing.An acoustic transducer is contained within a compartment within thehousing and is attached to the housing by a flexible line. A radiotransmitter is connected to the antenna for transmitting representationsof acoustic signals received by the acoustic transducer. Circuitry isresponsive to immersion of the housing in a body of water for moving theantenna to the extended position and for lowering the acoustictransducer from the housing into the water for a predetermined depth.Circuitry is also provided to delay the lowering of the acoustictransducer from the housing for a predetermined time after the housingis placed in the body of water.

oascanmon OF THE DRAWINGS For a more complete understanding of thepresent invention and for further objects and advantages thereof,reference is now made to the following descriptions taken in conjunctionwith the accompanying drawings, in which:

FIG. 1 is a diagrammatic illustration of a typical marine explorationprocedure utilizing the present sonobuoy;

FIG. 2 is a sectional view of the present sonobuoy with the antenna inthe extended position;

FIG. 3 is a perspective view of a portion of the present sonobuoy;

FIG. 4 is a perspective view of the present sonobuoy, with portionsthereof broken away, with the antenna in a retracted position, and

FIG. 5 is a perspective view of the lower portion of the presentsonobuoy during lowering of the hydrophone assembly.

Referring to FIG. I, a seismic exploration vessel is designatedgenerally by the numeral l0 and is illustrated as towing therebehind aseismic streamer 12 in the conventional manner. Such streamers extend upto lengths in the range of 10,000 feet. An acoustic source 14 is towedbelow the vessel 10 and is operated to generate sequences of acousticimpulses Suitable acoustic sources comprise air guns, gas explodingdevices and the like. Reflections of the acoustic signals from substrataare received by the seismic streamer l2 and are recorded onboard thevessel 10 for subsequent processing according to well known techniques.

A sonobuoy 16 according to the present invention is illustrated asubstantial distance from the vessel 10, which in practice may comprisea range of 8 to 12 miles. A plurality of sonobuoys 16 are sequentiallydeposited in the water from the vessel 10 during a traverse along aselected path. As will be later described, the sonobuoy 16 comprises acylindrical housing which is initially cast into the water from thevessel 10 in a deactivated state. The cylindrical housing floats on thesurface of the water for a predetermined time until the seismic streamer12 has been towed past the floating sonobuoy. After the predeterminedtime, which may be for instance about 20 minutes, sonobuoy l6automatically extends an antenna 20 which includes ground planeextensions 22. A lower compart ment 24 of the cylindrical sonobuoyhousing drops away from the main buoy housing and is maintained at apredetermined depth beneath the housing by a flexible line 26.

A hydrophone 28 is connected through a preamplifier 30 and viaelectrical connections through the line 26 to transmitter circuitrywithin the sonobuoy housing l6. A weight 32 maintains the hydrophone 28at the selected depth. The hydrophone 2B is thus positioned to detectrefraction signals generated by the acoustic source 14. The electricaloutput from the hydrophone 28 is transmitted via the line 26 to thetransmitter circuitry within the buoy housing 16. The transmitter thentransmits indications of the refraction data from the antenna 20 tosuitable receiver circuitry on board the vessel 10. The representationsof the refraction data are recorded on suitable recording apparatusonboard the vessel 10. The refraction data may be recorded by digital oranalog circuitry and is often plotted onboard the vessel in order toenable the results of the surveys to be immediately evaluated. The plotgenerated onboard the vessel generally takes the form of a travel-timediagram, wherein the time is registered by a sweep recording of thereturns from the acoustic source, while the distance is measured by thespeed of the ship between the periodic actuation of the acousticgenerator source 14.

Of particular importance with the use of the present sonobuoy is thedelay built into the buoy before automatic actuation, in order that thehydrophone 28 does not become entangled with the seismic streamer 12.

The present sonobuoy may be picked up by the vessel 10 and reused, butit will generally be more economical to provide structure for scuttlingof the sonobuoy 16 after a number of hours use due to the cost ofretracing of the path of vessel 10.

FIG. 2 illustrates in detail the construction of the present sonobuoy16. A main housing 40 provides an airtight compartment 42 between alower seal member 44 and an upper seal member 46. An audio circuit iscontained within the housing 48 for connecting the output of thehydrophone 28 to the transmitter circuitry contained within the housing50. In the preferred embodiment, the transmitter circuitry containedwithin the housing 50 operates at about one watt at channel frequencyafter activation and has a frequency stability within 5 KI-Iz of theselected channel frequency. The audio circuitry contained within housing48 frequency modulates the transmitter circuitry.

An antenna housing shaft 52 extends between the lower and upper sealmembers and slidably receives an antenna support shaft 54. The shaft 54is hollow and contains an antenna ejection spring 56 therein. Shaft 54carries a housing 58 on the end thereof. Housing 58 supports a coilspring 60 which is an integral part of the antenna 20. Housing 58 alsosupports the ground plane members 22. A release wire 62 is connected atone end to the housing 58 and extends down a tube 64 to a clip 66. Clip66 is attached to a fastener member 68. Fastener member 68 includes aslot which receives the head 70 of bolt 72. The head 70 of the bolt 72extends through an aperture in a circular weight member 74. Weightmember 74 is attached to a lower housing assembly 76. The fasteningmember 68 thus maintains the connection between the lower housingassembly 76 and the main housing 40. When the fastener member 68 ispulled away from the head 70 of the bolt 72, the lowe housing assembly76 is released as will be later described.

An electrical wire 80 leads from the transmitter circuitry to theantenna 20 to enable transmission of radio signals to the remote seismicexploration vessel. A burn wire 82 is shown in FIG. 2 in a brokencondition. As will be later described, burn wire 82 serves to retain theantenna assembly within the main housing 40 until the desired release. Aseawater battery 84 is attached to a leg of the lower seal member 44.When the present sonobuoy is disposed in seawater, battery 84 contactsthe water and becomes energized in the well known manner. Electricalleads, not shown, connect the battery 84 to the audio circuitry, thetransmitter circuitry and to the burn wire 82 through a suitable delaymechanism, as will be subsequently described. A scuttle plug 86 isdisposed through the side of the housing 40 and contains salt or asuitable similar material. Upon contact with the water, the saltdisintegrates the scuttle plug 86 and allows water inside the housing 40to sink the sonobuoy. The quantity of salt placed within the scuttleplug 86 determines the length of operating time before the sonobuoy isscuttled.

FIG. 3 illustrates in perspective the upper portion of the sonobuoy withthe housing 40 removed. The antenna assembly is illustrated in theprocess of moving from the retracted position within the housing 40 tothe extended position outside the housing 40. In the retracted positionof the antenna, the antenna 20 is bent around spring 60 and extendswithin the shaft 52. Additionally, the ground plane members 22 are bentto extend within the shaft 52. Upon release by the burn wire 82, thespring 56 pushes the shaft 54 upwardly. The antenna 20 and the groundplane members 22 then spring outwardly into the upright extendedposition.

f importance is the delay device 90 mounted on the underside of theupper seal member 46. Wires extend from the delay device 90 to thebattery 84 and from the delay device 90 to the burn wire 82. When thesalt water battery 84 is energized, current is applied to the delaydevice 90. A predetermined delay then occurs before current is appliedto the burn wire 82. When current is applied to the burn wire 82, thewire becomes heated and breaks, thereby allowing the antenna assembly tobe extended by the force of the spring 56 to the outwardly extendedposition.

The delay member 90 may comprise any suitable device such as anelectrolytic timer or a mechanical timer. In practice, a 20-minute delayhas been found satisfactory to enable a 9,000 foot seismic streamer tobe towed past the sonobuoy at approximately 5 knots.

FIG. 4 illustrates the upper portion of the sonobuoy 16, with two of theoutwardly extending legs of the upper seal member 46 being eliminatedfor illustration purposes. The sonobuoy 16 is in the deenergized mode,with the antenna 20 and the ground plane members 22 being disposedthrough a slot I00 into the shaft 52 as previously described. The burnwire 82 is intact and thus restrains the antenna assembly in theretracted position. When electrical current is applied to the burn wire82 from the delay mechanism 90, the burn wire breaks and the antennaassembly extends. During opening of the antenna assembly to the extendedposition, the release wire 62 is pulled upwardly to disengage thefastener device 68 from the head of the bolt 70, to thereby release thelower housing 76. Wire is coiled and restrained by a flexible rubbermember 102 in the deenergized mode of the sonobuoy. When the housing 58rises to the extended position, the wire 80 is pulled away from theflexible member 102 to connect the antenna with the transmittercircuitry.

Referring again to FIG. 2, the lower housing 76 includes an ejectionspring 106 for maintaining tension between the main housing 40 and thelower housing 76. The line 26, commonly termed the compliance section,is coiled within the lower housing 76. The bolt 72 is affixed at thelower end to a disc 1 12. The preamplifier 30 and the hydrophone 28 aredisposed in the lower housing 76 and maintained in place by the disc112.

FIG. 5 illustrates an exploded view of the dropping of the hydrophoneassembly from the sonobuoy 16. The head 70 of the bolt 72 is releasedwhen fastening device 68 is pulled upwardly due to the extension of theantenna assembly. The bolt 72 then slips downwardly in the water due tothe weight of the disc 112. The lower housing 76 is then released fromits connection with the lower seal member 44 and begins to descendthrough the water. The line or compliance section 26 unreels from thelower housing assembly during the descent of the lower housing assembly76, the hydrophone 28, preamplifier 30 and the weight 32 fall out fromthe bottom of the lower housing assembly 76 and extend to the positionshown in FIG. 1. Also during the descent, electrical power is suppliedto the hydrophone assembly and to the acoustic circuitry in order toenable the transmission of detected acoustic waves to the seismic marinevessel in the manner previously described.

Briefly summarizing the operation of the present sonobuoy, the sonobuoyI6 is placed in its deenergized mode in the water from the side of aseismic exploration vessel. The sonobuoy remains in the deenergizedposition for a predetermined period of time in order to prevententanglement of the hydrophone system with the trailing seismicstreamer. After the predetermined time delay, electrical power isapplied from the delay device to the burn wire 82. The burn wire 82breaks and the spring 56 forces the housing 58 upwardly. The antenna 20springs upwardly due to the coil spring 60 and the ground plane members22 spring outwardly. Electrical power is applied to the transmittersystem at this time.

As the antenna system is being erected, the wire 62 pulls the fasteningdevice 68 outwardly away from the head 70 of the bolt 72. The lowerhousing assembly 76 is thus released and the entire lower housingassembly begins to descend in the water. The line 26 is unreeled duringthis descent and the bolt 72 and the disc member 112 falls away from thebottom of the lower housing assembly 76. The hydrophone 28, preamplifier30 and weight 32 then descend to the desired depth for reception ofacoustic or seismic signals. Representations of the detected seismicsignals are transmitted by the transmitter circuitry through the antenna20 and received by a suitable antenna aboard the seismic marine vessel.

It will be understood that certain variations may be utilized with thepresent invention. For instance, the antenna 20 in some instances may beallowed to be erected initially, with a time delay being provided beforelowering of the hydrophone system. in this manner, initial ratiotransmission may be initiated from the sonobuoy prior to lowering of thehydrophone system. in some embodiments, an anchoring system may be alsolowered along with the hydrophone system.

Whereas the present invention has been described with respect tospecific embodiments thereof, it will be understood that various changesand modifications will be suggested to one skilled in the art, and it isintended to encompass such changes and modifications as fall within thescope of the appended claims.

What is claimed is:

1. A sonobuoy comprising:

a buoy housing containing acoustic transducer means,

means operable to lower said acoustic transducer means from said buoyhousing a predetermined period of time after said buoy housing is placedin a body of water,

radio transmitter means within said buoy housing for transmittingindications of acoustic signals received by said acoustic transducermeans,

battery means disposed within said housing and activated by contact withwater, and

release means for said acoustic transducer means and said antenna meansbeing responsive to the operation of said battery means.

2. The sonobuoy of claim 1 and further comprising:

antenna means movable from a retracted position within said housing toan extended position outside said housing.

3. The sonobuoy of claim I wherein the electrical output from saidbattery means causes the breakage of a wire restraining the release ofsaid acoustic transducer means and said antenna means.

4. The sonobuoy of claim 1 and further comprising:

delay means for delaying the application of the electrical output fromsaid battery to said wire for said predetermined period of time in orderthat said acoustic transducer means may avoid entanglement with a towedobstacle.

5. The sonobuoy of claim 1 and further comprising:

a flexible lead connecting said acoustic transducer means to said buoyhousing,

a lower housing attached to said buoy housing and containing saidacoustic transducer means and said flexible lead,

battery means responsive to water for generating an electrical output,and

means responsive to said electrical output for releasing said lowerhousing from said buoy housing after said predetermined period of time.

6. The sonobuoy of claim 1 and further comprising:

a spring loaded shaft mounted in the upper end of said buoy housing andoperable to extend upwardly from said buoy housing after said buoyhousing is disposed in a body of water,

antenna means initially bent at the upper end thereof in order to becontained within said shaft, and

spring means located in the upper bend portion of said antenna meanswherein when said shaft is upwardly extended said antenna means swingsupwardly into an extended position.

7. An automatically energized sonobuoy comprising:

a buoy housing including flotation structure,

antenna means movable from a retracted position inside said housing toan extended position outside said housing,

acoustic transducer means contained within a compartment in said housingand attached to said housing by a flexible line,

transmitter means connected to said antenna means for transmittingrepresentations of acoustic signals received by said transducer means,

means responsive to immersion of said housing in a body of water formoving said antenna means to said extended position and for loweringsaid transducer means from said housing into the water means fordelaying the lowering of said transducer means from said housing for apredetermined time after said housing is placed in the body of water,

battery means disposed within said housing and activated by contact withwater, and

release means for said acoustic transducer means and said antenna meansbeing responsive to the operation of said battery means.

8. The sonobuoy of claim 7 and further comprising:

a wire normally restraining the release of said acoustic transducermeans and said antenna means until electrical current from said batterymeans causes said wire to break.

9. The sonobuoy of claim 8 and further comprising:

delay means for delaying the application of the electrical output fromsaid battery to said wire for said predetermined period of time in orderthat said acoustic transducer means may avoid entanglement with a towedobstacle.

10. The sonobuoy of claim 7 and further comprising:

a flexible lead connecting said acoustic transducer means to said buoyhousing,

a lower housing attached to said buoy housing and containing saidacoustic transducer means and said flexible lead,

battery means responsive to water for generating an electri cal output,and

means responsive to said electrical output for releasing said lowerhousing from said buoy housing after said predetermined period of time.

1 l. The sonobuoy of claim 7 wherein said transducer means is containedwithin a lower housing attached to the bottom of said buoy housing byfastening means,

release means maintaining said antenna means in the retracted position,

battery means responsive to water to generate an output signal whichoperates said release means for release of said antenna means, and

means responsive to the movement of said antenna means to the extendedposition for actuating said fastening means to release said lowerhousing from said buoy housing.

a a a 4 is 2222330 UNITED STATES PA'LIQNT OFFlClB) CEH'EIZFICATE OFCUIUMIC'E.ION

Patent No. 3 671, 928 Dated June 20 1972 Inventor(s) James F Schult Itis certified that error appears in the above-identified patent and thatsaid Letters Patent are hereby corrected as shown below:

C01. 3, line 31, "lowe" should be lower-. Col. 4, line 40, after"housing" insert 76. During the descent of the lower housing-. Col. 5,line 1, "ratio" should be -radio.

Signed and sealed this 10th day of October 1972.

(SEAL) Attest:

EDWARD M.FLETCHER,JR. ROBERT GOTTSCHALK Attesting Officer Commissionerof Patents

1. A sonobuoy comprising: a buoy housing containing acoustic transducermeans, means operable to lower said acoustic transducer means from saidbuoy housing a predetermined period of time after said buoy housing isplaced in a body of water, radio transmitter means within said buoyhousing for transmitting indications of acoustic signals received bysaid acoustic transducer means, battery means disposed within saidhousing and activated by contact with water, and release means for saidacoustic transducer means and said antenna means being responsive to theoperation of said battery means.
 2. The sonobuoy of claim 1 and furthercomprising: antenna means movable from a retracted position within saidhousing to an extended position outside said housing.
 3. The sonobuoy ofclaim 1 wherein the electrical output from said battery means causes thebreakage of a wire restraining the release of said acoustic transducermeans and said antenna means.
 4. The sonobuoy of claim 1 and furthercomprising: delay means for delaying the application of the electricaloutput from said battery to said wire for said predetermined period oftime in order that said acoustic transducer means may avoid entanglementwith a towed obstacle.
 5. The sonobuoy of claim 1 and furthercomprising: a flexible lead connecting said acoustic transducer means tosaid buoy housing, a lower housing attached to said buoy housing andcontaining said acoustic transducer means and said flexible lead,battery means responsive to water for generating an electrical output,and means responsive to said electrical output for releasing said lowerhousing from said buoy housing after said predetermined period of time.6. The sonobuoy of claim 1 and further comprising: a spring loaded shaftmounted in the upper end of said buoy housing and operable to extendupwardly from said buoy housing after said buoy housing is disposed in abody of water, antenna means initially bent at the upper end thereof inorder to be contained within said shaft, and spring means located in theupper bend portion of said antenna means wherein when said shaft isupwardly extended said antenna means swings upwardly into an extendedposition.
 7. An automatically energized sonobuoy comprising: a buoyhousing including flotation structure, antenna means movable from aretracted position inside said housing to an extended position outsidesaid housing, acoustic transducer means contained within a compartmentin said housing and attached to said housing by a flexible line,transmitter means connected to said antenna means for transmittingrepresentations of acoustic signals received by said transducer means,means responsive to immersion of said housing in a body of water formoving said antenna means to said extended position and for loweringsaid transducer means from said housing into the water, means fordelaying the lowering of said transducer means from said housing for apredetermined time after said housing is placed in the body of water,battery means disposed within said housing and activated by contact withwater, and release means for said acoustic transducer means and saidantenna means being responsive to the operation of said battery means.8. The sonobuoy of claim 7 and further comprising: a wire normallyrestraining the release of said acoustic transducer means and saidantenna means until electrical current from said battery means causessaid wire to break.
 9. The sonobuoy of claim 8 and further comprising:delay means for delaying the application of the electrical output fromsaid battery to said wire for said predetermined period of time in orderthat said acoustic transducer means may avoid entanglement with a towedobstacle.
 10. The sonobuoy of claim 7 and further comprising: a flexiblelead connecting said acoustic transducer means to said buoy housing, alower housing attached to said buoy housing and containing said acoustictransducer means and said flexible lead, battery means responsive towater for generating an electrical output, and means responsive to saidelectrical output for releasing said lower housing from said buoyhousing after said predetermined period of time.
 11. The sonobuoy ofclaim 7 wherein said transducer means is contained within a lowerhousing attached to the bottom of said buoy housing by fastening means,release means maintaining said antenna means in the retracted position,battery means responsive to water to generate an output signal whichoperates said release means for release of said antenna means, and meansresponsive to the movement of said antenna means to the extendedposition for actuating said fastening means to release said lowerhousing from said buoy housing.